Hyperhidrosis Disease Severity Measure-Axillary (HDSM-Ax): Evaluation of Measurement Performance

Background: Clinical trials of primary axillary hyperhidrosis (AHH) require rigorous measurement of AHH severity from the patient’s perspective. Previously, we reported conceptualization and item content development for the Hyperhidrosis Disease Severity Measure-Axillary (HDSM-Ax) scale.
Objective: To evaluate the psychometric performance and estimate clinically meaningful change scores for the HDSM-Ax in a Phase IIb clinical study of sofpironium bromide gel for AHH.
Method: HDSM-Ax measurement performance was analyzed in trial response data using two psychometric paradigms: Classical Test and Rasch Measurement Theories (CTT; RMT). HDSM-Ax meaningful change scores were estimated from anchor-based methods using two global summary questions of hyperhidrosis severity and the Hyperhidrosis Disease Severity Score (HDSS).
Results: HDSM-Ax satisfied CTT and RMT criteria as a fit-for-purpose outcome measure in AHH clinical trials. Within-person anchor-based analyses indicated a 1-point change in HDSM-Ax severity score (range, 0–4) represents a clinically meaningful change in AHH severity.
Conclusion: HDSM-Ax is a well-defined and reliable measure of AHH severity. A 1-point change in HDSM-Ax score is clinically meaningful.